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#!/usr/bin/env python3
"""
Audit Logging Middleware for DocuElevate.
This middleware logs all HTTP requests and security-relevant events. Sensitive
data (passwords, tokens, secrets, API keys) is masked before logging so that
credentials are never recorded in application logs.
Security-relevant events that receive elevated ``[SECURITY]`` log entries:
- Authentication failures (401 Unauthorized)
- Authorisation denials (403 Forbidden)
- Login / logout endpoint access
- Server errors (5xx responses)
Logged per request:
- HTTP method
- Request path (query-param values for known sensitive keys are replaced with ``[REDACTED]``)
- Response status code
- Response time in milliseconds
- Client IP address (configurable)
- Authenticated username when available
See SECURITY_AUDIT.md Infrastructure Security section for background.
"""
import logging
import re
import time
from typing import Callable
from fastapi import Request, Response
from starlette.middleware.base import BaseHTTPMiddleware
logger = logging.getLogger(__name__)
# Query-parameter / form-field names whose *values* must never appear in logs.
# Matching is case-insensitive.
_SENSITIVE_PARAM_PATTERN = re.compile(
r"^(password|passwd|pwd|secret|token|access_token|refresh_token|"
r"api_key|apikey|key|credential|credentials|auth|authorization|"
r"client_secret|private_key|session)$",
re.IGNORECASE,
)
# HTTP headers whose values must never appear in logs.
_SENSITIVE_HEADERS = frozenset(
{
"authorization",
"cookie",
"set-cookie",
"x-api-key",
"x-auth-token",
}
)
# Endpoints considered security-sensitive for elevated logging.
_AUTH_PATHS = frozenset({"/auth", "/login", "/logout", "/oauth-login", "/oauth-callback"})
def mask_query_string(query_string: str) -> str:
"""
Replace values of sensitive query parameters with ``[REDACTED]``.
Args:
query_string: Raw URL query string (e.g. ``"user=alice&password=secret"``).
Returns:
Query string with sensitive values replaced.
"""
if not query_string:
return query_string
parts = []
for pair in query_string.split("&"):
if "=" in pair:
name, _, value = pair.partition("=")
if _SENSITIVE_PARAM_PATTERN.match(name):
parts.append(f"{name}=[REDACTED]")
else:
parts.append(pair)
else:
parts.append(pair)
return "&".join(parts)
def get_client_ip(request: Request) -> str:
"""
Extract the real client IP, honouring X-Forwarded-For when present.
Args:
request: Incoming HTTP request.
Returns:
Client IP address string.
"""
forwarded_for = request.headers.get("x-forwarded-for")
if forwarded_for:
# Take only the first (leftmost) address that is the original client.
return forwarded_for.split(",")[0].strip()
if request.client:
return request.client.host
return "unknown"
def get_username(request: Request) -> str:
"""
Extract the authenticated username from the session, if available.
Args:
request: Incoming HTTP request.
Returns:
Username string, or ``"anonymous"`` when not authenticated.
"""
try:
user = request.session.get("user") if hasattr(request, "session") else None
except Exception:
user = None
if not user:
return "anonymous"
if isinstance(user, dict):
return (
user.get("preferred_username")
or user.get("username")
or user.get("email")
or user.get("id")
or "authenticated"
)
return str(user)
class AuditLogMiddleware(BaseHTTPMiddleware):
"""
Middleware to log HTTP requests and security-relevant events.
Each request produces a single ``INFO``-level audit log line.
Requests that result in 401/403 responses, or that target
authentication endpoints, additionally produce a ``WARNING``-level
security event line. Server errors (5xx) produce an ``ERROR``-level
security event line.
Configuration is read from the application settings object passed at
construction time via the ``config`` keyword argument.
"""
def __init__(self, app, config) -> None:
"""
Initialise the audit-log middleware.
Args:
app: FastAPI / ASGI application instance.
config: Application settings object (must expose
``audit_logging_enabled`` and
``audit_log_include_client_ip`` boolean attributes).
"""
super().__init__(app)
self.enabled = config.audit_logging_enabled
self.include_ip = config.audit_log_include_client_ip
if self.enabled:
logger.info(f"Audit logging middleware enabled (include_client_ip={self.include_ip})")
else:
logger.info("Audit logging middleware disabled")
async def dispatch(self, request: Request, call_next: Callable) -> Response:
"""
Process the request, call the next handler, then emit audit log entries.
Args:
request: Incoming HTTP request.
call_next: Next middleware or route handler in the chain.
Returns:
HTTP response (unmodified).
"""
if not self.enabled:
return await call_next(request)
start_time = time.monotonic()
response = await call_next(request)
duration_ms = int((time.monotonic() - start_time) * 1000)
self._log_request(request, response.status_code, duration_ms)
return response
# ------------------------------------------------------------------
# Private helpers
# ------------------------------------------------------------------
def _build_path_with_masked_query(self, request: Request) -> str:
"""Return the request path with sensitive query-param values masked."""
path = request.url.path
raw_query = request.url.query
if raw_query:
masked = mask_query_string(raw_query)
return f"{path}?{masked}"
return path
def _log_request(self, request: Request, status_code: int, duration_ms: int) -> None:
"""
Emit audit log entries for a completed request.
Args:
request: The HTTP request object.
status_code: HTTP response status code.
duration_ms: Total request processing time in milliseconds.
"""
method = request.method
path = self._build_path_with_masked_query(request)
username = get_username(request)
ip_part = f" - {get_client_ip(request)}" if self.include_ip else ""
# Core request log line (always INFO).
logger.info(f"[AUDIT] {method} {path} {status_code} {duration_ms}ms{ip_part} - {username}")
# Security-event log lines for noteworthy conditions.
self._log_security_event(method, path, status_code, username, ip_part)
def _log_security_event(
self,
method: str,
path: str,
status_code: int,
username: str,
ip_part: str,
) -> None:
"""
Emit an additional security-event log line when warranted.
Args:
method: HTTP method (GET, POST, …).
path: Sanitised request path (with masked query params).
status_code: HTTP response status code.
username: Authenticated username or ``"anonymous"``.
ip_part: Pre-formatted IP string (may be empty string).
"""
base_path = path.split("?", maxsplit=1)[0]
if status_code == 401:
logger.warning(f"[SECURITY] AUTH_FAILURE {method} {path} 401{ip_part} - {username}")
elif status_code == 403:
logger.warning(f"[SECURITY] ACCESS_DENIED {method} {path} 403{ip_part} - {username}")
elif base_path in _AUTH_PATHS and method == "POST":
# Login attempts (successful or not) are always noted.
logger.info(f"[SECURITY] AUTH_ATTEMPT {method} {path} {status_code}{ip_part} - {username}")
elif status_code >= 500:
logger.error(f"[SECURITY] SERVER_ERROR {method} {path} {status_code}{ip_part} - {username}")